Wednesday, 30 August 2017

The
“standard aurochs colour scheme” is as it follows: bulls being more or less
completely black except a dorsal stripe and a muzzle ring of a light colour
(whether there were also bulls with lightly coloured forelocks is unknown). For
cows, various shades from completely reddish-brown, dark brown or black with a
reddish-brown back/colour saddle and also “bull colour” are supported by
evidence.

There is
not one good reason to assume that European aurochs bulls had a colour saddle,
but at least some North African aurochs (I tend to think it was universal in
this subspecies) had one, as outlined in my post on Bos primigenius africanus. For the Indian aurochs, nothing is known
of its life appearance except for what goes beyond osteologic information, but
we can speculate (emphasis on speculate) that it might have had a very similar
colour to that of the European aurochs, but it could also had some differences
as I outlined in the posts on Bos
primigenius namadicus (the most recent and most comprehensive one here).

But apart
from what is either proven or at least not implausible based on the evidence,
could there have been some more colour variants? The aurochs’ original range
was quite large, and genetic drift and habitat differences could have produced
some local variants, or some that were limited in time, or perhaps such that
were so rare and unremarkable that they were not noticed. I made some thoughts
on that, and also illustrated them and would like to share them with you in
this post. I am going to start with the hypothetical colour variants that I
consider most likely and end with the least likely one.

1: Completely black aurochs

The degree
to which the muzzle ring and the dorsal stripe were expressed may have varied.
Usually, as wildtype coloured cattle age, the muzzle ring gets reduced and may
even almost disappear except for the chin (mostly in bulls). I would not be
surprised if some or many wild aurochs bulls also showed only reduced muzzle
rings or none at all, which might be the reason why there are no
contemporaneous literature references to this trait. In Bantengs and Gaurs, we
have the same situation – some individuals show them, others do not. Some
aurochs bulls may have even lacked a dorsal stripe. But that is not what I am
thinking about here. I am talking about the possibility that the Ed allele was actually
present in wild aurochs populations before domestication and is actually a
second wild type allele of the Extension
locus. In this case, some aurochs would have been completely black in both
sexes without any light markings, as we see it in many breeds (f.e. Angus, many
fighting bulls et cetera). Usually, wild animal populations are quite uniform
regarding coat colours, but the phenotypic difference between E+and Ed, especially in bulls,
would be so marginal that I hardly believe natural selection would have purged
it out again in a few millennia after aurochs spread to Europe from the Middle
East.

We cannot
say there is direct evidence for this colour variant to have been present in
Aurochs. Surely a lot of sources just describe the aurochs simply as “black”
(f.e. Plinius), but that would also be the case if someone would describe an E+ bull without making the
effort of making an extra remark on the light markings.

This is what aurochs with an Ed phenotype would look like:

The only
way to test if there were Ed
aurochs would be to do a genetic test for coat colour alleles in aDNA of fossil
and subfossil aurochs material, as it has been done for wild horses in recent
years.

I think
that would be worth examining it, as I consider the possibility of aurochs with
the Edallele absolutely
plausible. If it was found in Holocene or historic aurochs only, it may also be
possible that the black allele would still be of domestic origin and found its
way into the wild population by domestic introgression. Domestic animals escape
all the time all over the world and can leave a mark in wild populations,
especially in the form of colour variants as they are most neutral to
selection. This is evident in some wolf and wild boar populations, and the same
happened in wild horses in Europe, where the e mutation (sorrel) got into wild populations in historical times
(Pruvost et al. 2011). So it might have happened in Holocene aurochs as well,
and the black mutation would maybe not have been discernable for eyewitnesses.

2: Red aurochs in far Eastern Europe

Casta-Navarra bull showing the red colour of a cow

Many of you
know this chart showing the maximum range of the aurochs. The way I understand
it, it shows the sum of all ranges the aurochs originally had, and not where it
once ranged all at the same time. It seems that the aurochs was not an animal
of the steppes, it would probably not do well in the cold and dry Eurasian
steppe of the Baikal area. There are bone findings from this area, but from a
time when climate was warmer and allowed Bos
primigenius primigenius, adapted to the temperate European climate, to live
there. That is why the Holocene range of the aurochs ended in the west of
Russia in the transition zone from the European temperate biome to the Eurasian
steppe biome. What is interesting is that van Vuure notes that Russian and
Romanian tales tell of “red aurochs”, while most Central and European
literature refers to “black aurochs” or mention sexual dimorphism. Could that
mean that the aurochs of far eastern Europe in the semi-steppe lacked sexual
dimorphism and that their bulls were of a red colour, perhaps caused by genetic
drift? This would add another colour variant to the list, and quite frankly, it
would be very interesting.

But I
consider the evidence for that too weak. First of all, folk tales are not all
too precise. Furthermore, cattle usually form herds of cows with calves and
young bulls, where most individuals would be of a red colour, and bulls form
either small groups of youngsters or wander around solitarily. So the chance is
good that when people thought of big herds of aurochs most individuals would
have been red because they consisted of cows, calves and young bulls. Again,
genetics could resolve this question, but examining the amount of sexual
dichromatism would probably go less quick than just a test for colour alleles.

3: Aurochs with the White Park pattern

The cave
paintings at Lascaux are from the Paleolithic and about 17.000 years old. It
includes black bulls, red cows, and line drawings showing bulls. What is
peculiar about these line drawings is that they show small, irregular black
spots on the neck, face and shoulder area, distributed in the same kind of
pattern we find in the British breeds White Park and Chillingham cattle. This
colour variant is caused by the homozygous presence of the Colour sided allele Cs.
Could it be that some, perhaps only Pleistocene Southern European aurochs showed
the so-called White Park pattern? This is not entirely implausible, and I
revealed this idea in 2013 already. Cave paintings also show spotted horses
long before the emergence of domestic horses, and a study by Pruvost et al.
2011 showed that such spotted wild horses probably did exist and where no
invention of Pleistocene artists. So why should not be the same possible here?

It seems
that these line drawings at Lascaux would be the only evidence supportive of
this idea. There are no artistic or literary references that ever mention white
or very faintly coloured aurochs, not even mystery tales. But this colour
variant must have survived in the aurochs population until at least 8.500 years
ago when the first aurochs where domesticated, otherwise it would not be found
among domestic cattle. Interestingly, the heterozygous state Cs/cs+ results in a spotted
colour called “colour sided”, found in many Texas Longhorn, for example. So if
aurochs with the White Park pattern would have mated with typically coloured
aurochs, “colour sided” aurochs would be the result – such a piebald colour is
rather untypical for wild animals and probably of selective disadvantage
(camouflage, especially for calves). However, a disadvantageous heterozygous
state is not impossible for a wildtype allele. An aurochs with a “colour sided”
pattern would have probably been considered a hybrid by eyewitnesses, but there
are no contemporaneous notions of (alleged) aurochs-cattle hybrids running
around in the wild that I am aware of.

In any case,
the line drawings from Lascaux are the only evidence that would support a White
Park pattern in aurochs, but the small black spots can also be interpreted
differently. Perhaps the artist wanted
to indicate curly hair. Many domestic bulls, especially those of populations/breeds
where the bulls fight on regular basis (Chillingham, Betizu, Eringer, Lidia,
some Heck cattle at Oostvaardersplassen), often have rather curly hair on head,
neck, face and shoulder area what – I hypothesize – might protect their skin in
a fight. Some, or even all, wild aurochs bulls might have had this trait as
well (the curly hair between the horns is proven in any case). See this post.

So the
evidence for this colour variant is very weak, but it could be worth to test
aDNA from the suspected population (Southern European aurochs of the
Pleistocene) for the Cs allele.

Note that I
am neither saying that I “believe” these colours were present in wild aurochs,
nor do I say that I consider that likely. I am just speaking of possibilities.
To test these ideas, genetic tests of historic and prehistoric aurochs aDNA
would be necessary. The same work has been done with wild horses, and revealed
surprises. It is likely that testing aurochs would result in a confirmation of
status quo, but it would be worth examining. However, the problem is that there
is way fewer interest in cattle as animals than in horses and many geneticists
might consider genetically examining the colour of wild aurochs too trivial.

Saturday, 26 August 2017

This is a
topic that has been barely covered here before, but is surely of interest for
many of my readers especially since the 2015 article on the genetic studies
involved in the Tauros Project was published by Rewilding Europe. The reason
why I have covered neither the article nor the issue of genetic proximity here as
such is that it is a lot to write and explain, and I haven’t had the time
previously. However, this summer I have the time and inspiration to finally
cover this topic appropriately.

By genetic
proximity, we of course refer to the genetic proximity of living domestic
cattle to its wild progenitor, the Eurasian aurochs Bos primigenius primigenius. But there are several ways in which domestic
cattle can be “close to their ancestor”, several ways how genetic proximity is
defined or measured, and what it implicates for “breeding-back”. However, as I
always admit, I myself am a layman in the field of genetics so please point me
to mistakes if I made some.

What was
especially striking when Rewilding Europe published their article on genetics
was the chart of Nei genetic distance of a number of cattle breeds to the
aurochs. The most obvious result is that there is seemingly no clear
correlation between a less-derived phenotype and “genetic proximity” (see down
below), which led some people to conclude that “genetics don’t matter”. But
genetics do matter of course: if you insert an aurochs’ genome into a Holstein
zygote, you get an aurochs. But why this discrepancy? To solve this question
and to find out what it means for “breeding-back”, we have to look at what
“genetic proximity” means in this case.

Of course
it would be best and most comprehensive to compare the full length of two
genomes against each other. However, as genomes are huge molecules with a lot
of information (in the case of cattle, the genome includes 3 billion base pairs
and 22.000 genes), this would be very effortful. And apart from that, only a
very small fraction of the whole genome codes for the defining differences
between closely related species, and an even smaller portion codes for
individual variation. So in order to make it easier, geneticists often rely on easily
identifiable, short DNA sequences such as marker genes, and haplotypes of the
mitochondrial genome or Y chromosomes. The advantage of molecular marker genes,
such as cytochrome c and others, is
that there is a constant average mutation rate per generation and that they are
barely effected by selection as they have minor influence on the individual
phenotypic variation, especially because many variations are neutral. This also
makes them useful for determining the time of splitting up between evolutionary
lines (“molecular clock”, the markers being used are called molecular
chronometers). While variations on the mitochondrial genome, Y chromosome and their
haplogroups as well as other marker genes are often used to determine the time
of divergence or degree of genetic proximity under the assumption of a constant
mutation rate and that they are barely affected by phenotypic selection, their
influence on the actual phenotype and thus the nature of the animals is
comparably minor. Mitochondrial genes mostly serve functions in the
mitochondria themselves, and there are only a few genes on the Y chromosome
that are actually relevant (lying on the sex-determining region of the
chromosome). Haplotypes (variations passed on by only one parental lineage) are
often used as an indicator of relatedness, but they actually are just an
accumulation of more or less neutral variation on haplotypes and their
influence on the organism as a whole is really minor. That is why the variation
on those markers usually studied are barely affected by selection, what makes
them in turn good markers. But their influence on the genetic architecture of
the animals is meagre. They can indicate relatedness, but do not guarantee that
the rest of the genome, especially those regions coding for the particular
differences between the taxa compared, will be similar too.

As an
example: let us assume that we take the genome of an ordinary Holstein-Frisian
and exchange all sequences of its marker genes, haplotypes and even the
complete mitochondrial genome with those sequences of an original aurochs and
let that embryo develop. The result will still be a Holstein-Frisian, because
the genetic material exchanged are mostly more or less neutral variations on
genes that have a minor influence on the individual variation within a species
or even between related species and not the regions that define the differences
between a Holstein-Frisian and an aurochs. A Holstein cow with aurochs
mitochondria would still be a Holstein cow in our perception, because the
influence of mitochondrial DNA of the organism as a whole is comparably small.
Furthermore, haplotypic variation does neither determine the identity of an
individual or a species.

Most of the
identity of an organism is defined by the nuclear genome. If you want to
determine truly influential differences between aurochs and cattle, you would
have to look there. Which is why the geneticists cited in the Rewilding Europe
article have had a look at nuclear autosomal SNPs (Single nucleotid
polymorphisms). SNPs, as long as they lie on coding regions, do have an
influence on the phenotype. Many mutations causing cancer in humans, for
example, are SNPs. For the study, 770.000 SNPs have been investigated and
compared between one aurochs individual and 35 cattle breeds. They calculated
the Nei genetic distance and presented the results (shown above).

The genetic
difference between wild aurochs and domestic cattle

As far as
my understanding goes, the last word is surely not spoken with that. It is of
course state of the art to measure genetic distance using SNPS, haplotypes,
marker genes et cetera, but we have again to look at the relevant genetic
differences between aurochs and cattle. Just as the aurochs was neither defined
via its mitochondria or haplogroups, it also was not defined by a couple of
thousand SNPs. I imagine that the truly vital genetic differences between an
aurochs and domestic cattle concern the following biological aspects:

- neurology

-
endocrinology

-
developmental regulation: timing et cetera

- sexual
dimorphism

-
metabolism

-
morphologic aspects

-
immunology

As outlined
in a number of previous posts where you also find relevant literature (here and
here), a lot of the differences between domestic and wild morphology are
probably caused by pleiotropic effects and developmental cascades and therefore
concern the upper five points; probably only a few novel morphological
mutations appeared (alleles such as those causing scurred horns, new colour
variants, extreme cases of dachshund-leggedness etc.).

I think
those seven aspects are where we should look for the defining genetic
differences between cattle and Eurasian aurochs that have a large biological
impact since they are probably those regions that determine whether we have to
deal with an aurochs or domestic cattle. Presenting the full genome sequencing
of a British aurochs, Park et al. 2015 noted that “important questions remain unanswered, including […] which genomic
regions were subject to selection processes during and after domestication. […]
Finally, the functions of genes showing evidence for positive selection in B.
taurus are enriched for neurobiology, growth, metabolism and immunobiology,
suggesting that these biological processes have been important in the
domestication of cattle”1, what fully supports my view.

It is
therefore my suspicion that we really have to identify the regions coding the
neurobiological, developmental, endocrinologic, morphologic, metabolic and
immunologic differences between aurochs and domestic cattle if we want to make
genetic comparisons that truly matter on a wider biological basis concerning
the nature of the animals and not coincidental variations that have been
accumulated on regions that are barely effected by selection.

It is
therefore not surprising that standard genetic methods that are usually used to
determine simple “relatedness” that look at marker sequences, be it haplotypes,
mitochondrial genes, SNPs or molecular chronometers that are not deeply
effected by phenotypical selection do not show a clear correlation between a
less derived and a strongly derived phenotype, although the latter clearly
implicates a lot of strong directive selection and mutations.

There are
multiple angles to look at a genome, and if we would look at those regions
named above that are probably where we should look for matches with the
aurochs, we would probably receive a different picture because those regions
are directly and highly involved in the shape, form and function of the
organism and directly and highly affected by phenotypic selection.

Furthermore,
and to come back to the chart presented by Rewilding Europe, I am not sure if
the Nei distance is the right tool to compare aurochs and cattle. The Nei
distance was developed to look at the divergence of populations via mutation
and genetic drift. In the case of cattle we do not have nice clean
cladogenesis, but at first we have a dramatic bottleneck, then strong selective
pressure during domestication, then very likely also local introgression on
multiple regions by different regional variants of aurochs, and, not to forget,
very unequal selective pressure on the different populations/lines/breeds of
domestic cattle we see today.

Implications
for “breeding-back”

So we would
actually have to clearly determine those particular regions determining the
defining differences between aurochs and cattle and get an overview over the allelic
differences there. I do not think that it is a problem that we have only one
full aurochs genome yet, because those traits defining the aurochs will,
unsurprisingly, be universal among aurochs. However, I do not think that the
results will be that enchanting or provide an additional directive for
“breeding-back” projects, because of two reasons: 1) the fundamental
differences between aurochs and domestic cattle concerning the seven factors
above will probably be more or less universal among domestic cattle because all
of them show the typical traits of domestication to a more or less clear
extent. It would surprise me if we could still find the genetic make-up for all
defining wild aurochs traits split up and distributed among the cattle of this
world. This could be expected if domestication was an uncoordinated process
where each of the factors was modified separately, which was certainly not the
case as an organism functions as a whole and domestication was a coordinated,
conscious process with a clear objective 2) certainly some breeds will be
closer to the aurochs than others, but the question is how much and if the
extent is relevant at all. For example, if the phenotypically most primitive cattle
on this world show a 1,01% match to the aurochs on those seven crucial factors
(just a symbolic number) while the most domesticated cattle show a 1,009%
match, then the difference has to be considered negligible despite the
primitive cattle having a number of alleles for a primitive morphology. I don’t
think the difference would be that small, but I also do not expect any
miraculous surprises. I think that all domestic cattle on this world are pretty
similar in being domestic, with the derived examples of course carrying it to
the extreme concerning a few morphological and other traits.

The claim
that “no aurochs genes were lost, but just split up and distributed among
domestic cattle” that has been floating around in the web for a while not only
has no empirical support but is also to be considered unlikely for the reasons
outlined above. The dramatic genetic effect of domestication – a narrow genetic
bottleneck at first, strong selection on a large number of genes that have a
dramatic influence on fundamental aspects of the organism – probably
irreversibly and universally purged off a lot of defining wildtype alleles and
therefore aurochs alleles from the domestic cattle gene pool, creating modern
domestic cattle. The occasional local introgression of aurochs may have left
traces in the modern domestic cattle pool (especially in the form of
immunologic adaptions etc.) but certainly it did not alter their domestic
nature. And even if all the defining aurochs genes were indeed still present in
the modern domestic gene pool, and even if we had already identified and
tracked them down in the populations, one should not make illusions over uniting
them by conventional breeding in an anywhere near future because we are probably
talking about at least hundreds of gene loci here. Body size alone is
determined by over 50 loci (in humans)2, and you already see how longsome
it is to achieve the right colour setting although we are dealing only with a
couple of genes there. Therefore, truly genetically reconstructing the aurochs by
selective breeding would be a centuries-long project, and many of the key genes
are probably lost anyway. It would probably be way faster, cheaper and endlessly
more effective to genetically reconstruct an aurochs via either cloning or CRISPR-Cas9.

Therefore, studies
on genetic markers and SNPs are nice, but we are certainly not looking at the
key genes that are relevant for true genetic identity of the animal that the
aurochs originally was. Furthermore, there are unfortunately good reasons to
assume that many of those defining key genes are lost due to the dramatic
process of domestication that all of our modern day cattle went through. That
is why you read that few on “genetic proximity” on this blog. We don’t know
what truly matters yet, and it is likely that we also don’t have it anymore. Thus,
I fear that I have to say that claiming “we are genetically breeding-back the
aurochs” is the same kind of simplicity once practised by the Heck brothers, just
carried onto the next level – even if you back it up with marker or SNP analyses. Please
do not get me wrong, this is just the personal opinion of a biology student sitting
in front of its laptop, therefore I am open for any critique.

Wednesday, 23 August 2017

In 2013 and
2015 respectively, I did posts on the Indian aurochs, Bos primigenius namadicus, the wild predecessor of zebuine cattle, each
time supported by an artistic reconstruction I made for the subspecies.

However, in
this post I want to start from a new and go systematically over what we know
about this divergent subspecies and what it might have been like. Bos primigenius namadicus is very
enigmatic – based on current evidence, survived until 8.000 years ago at
maximum, and there are no unambiguous artistic references and of course no
literary references to the wildtype of the zebu.

Before we
dive medias in res, I want to define some expressions: when I use the term “taurine
clade”, I do not refer to taurine cattle exclusively, but all animals that are
on the branch of taurine cattle since the branches of taurine and zebuine
cattle diverged, so also B. p. africanus
and B. p. primigenius of course. The
same goes with “zebuine clade”, it includes also B. p. namadicus. The namadicus-clade
is therefore synonymous with the zebuine clade, and the primigenius-africanus clade with the taurine clade (note that I am
talking about clades).

Phylogenetic evidence

While B. p. primigenius and B. p. africanus were pretty much alike,
seems as if the Indian aurochs was a kind of the “weirdo” of the species, and
its descendants, zebus, are still the weirdoes among cattle. Part of the reason
might be that the namadicus-clade
split up from the primigenius-africanus
clade rather early about 1,7-2 million years ago [1]. That is more
than one million years earlier than the oldest remains that have been assigned
to Bos primigenius [2]. That
is ten times the time distance between the domestic horse and Przewalski’s
horse [3]. One might ask why listing them as part of one species
then, and indeed the use of zebus as a species separate from that of taurine
cattle is widespread. However, taurine cattle and zebuine cattle still hybridize
readily without any problems, what supports classifying them and of course all
their ancestors back to their point of divergence 1,7-2mya as one species. It
is my preference to refer to this species as Bos primigenius. Nevertheless, meiotic chromosome pairing
abnormalities in zebuine x taurine hybrids suggest that postzygotic isolation
mechanisms were starting to develop, what suggests a beginning state of
speciation [1]. But subspecies are always “incipient species”, as
already noted by Darwin more than 150 years ago. As taxonomy is often
subjective and species definition is a very tricky issue (I have been planning
to do a post on that topic for a while), the differences might be enough for
some to regard the members of the taurine clade (and therefore also B.p. primigenius and B. p. africanus) and the zebuine clade
(and therefore also B. p. namadicus)
as separate species. In this case, the Indian aurochs would be no aurochs, but
you could still call the species like this, since it is its Indian sister
species. An alternative suggestion that I have would be wild zebu for the wildtype. You can still use the term wild zebu if
you consider namadicus an aurochs
subspecies.

So it seems
that the ancestors of Bos primigenius
namadicus migrated pretty early from Africa to India, while the common
ancestors of the primigenius-africanus
clade stayed in Africa for another while. This early divergence alone probably
might explain a part of the differences we see between namadicus and other aurochs populations.

Ecology

If the
Indian aurochs was ecologically similar to other wild members of the species,
it would have preferred semi-open landscapes near rivers and floodplains. In
India, it was sympatric with gaurs and water buffalo, and their respective
ecological niches supports this idea: gaurs prefer to live in more forested
areas, and water buffalo prefer more wet habitats. Therefore, we would see
niche partitioning between the three bovine species if the Indian aurochs was
ecologically comparable to the other two aurochs subspecies. Modern zebus often
are adapted to very arid habitats, but that is probably a consequence of the
fact that they are the cattle of people living in very arid regions. So this
does not necessarily indicate that namadicus was particularly adapted to arid
habitats.

Morphology and external appearance

The
morphology and life appearance of Bos
primigenius namadicus is not very well known. In contrast to B. p. primigenius, where we have plenty
of well preserved, more or less complete material, we only have fragmentary
postcranial material and a few skulls for the Indian subspecies (van Vuure,
2005). In order to resolve what namadicus’
life appearance was like, we have three sources of evidence and clues:

- Direct
evidence

- Parsimony
based on phylogenetic bracketing

- Zebuine
traits that might be wildtype traits of namadicus

Now let us
have a look at what we can deduce for the life appearance of B. primigenius namadicus, the Indian
aurochs or wild zebu if you will.

Direct
evidence:

Direct
evidence is what the bone material tells us. We have no unambiguous artistic
references to namadicus (this rock
art might or might not show an Indian aurochs; the horn tip might be tufted to
it could also be a Kouprey). So we have to rely solely on the scarce bone
material.

It seems
that the Indian aurochs was smaller than the European subspecies. I was unable
to find measurement data in the literature. I remember that Cis van Vuure
mentioned that the size of one Indian cranium was comparable to that of an
European aurochs cow. So perhaps 150-160cm is reasonable for bulls of the
Indian subspecies, which was the lower size end for European aurochs bulls.

This is the
only illustration of bone material from namadicus
that I was able to find. I will refer to it as the Lydekker skull. It is not
clear which sex it is; its eye sockets are not nearly as expressed as in
European aurochs bulls, and it is narrow in build. This does not necessarily
imply it is a female skull. Perhaps bulls of namadicus had a narrower skull with less prominent eye sockets. We
cannot say yet (at least I cannot, having seen only this one skull). The
drawing also does not enable to tell the exact orientation of the horns
relative to the skull, but it is apparent that they face more upwards and less
inwards than in many European skulls. The literature says that the horns of the
Indian subspecies were larger in proportion and more wide-ranging than in
European aurochs. Considering that basal aurochs and basal members of Bos (such as B. acutifrons, B. buiaensis)
had very large horns, it would perhaps be more correct to say the horns of the
Indian aurochs never shrank down, while some single Northern European aurochs
had horns that were not necessarily what I understand as “large” (see here, for
example). What definitely changed as namadicus
diverged was the orientation of the horns. Basal aurochs had horns at a rather
sharp angle (45° in the case of the oldest cranium), inherited from its
ancestors. The horns of the Indian aurochs were definitely more upright. This
might have been a result of genetic drift. So being proportionally large,
wide-ranging and comparably upright, the horns of the Indian subspecies might
have resembled those of Heck cattle of the Wörth lineage (see here, for
example) and a number of Watussi albeit not that huge. This analogue also fits the Lydekker skull.

This is all
that we can say based on osteological evidence.

- Parsimony
based on phylogenetic bracketing

This is a
way of reasoning that enables us to deduce traits that namadicus must have had even if we have no direct evidence for it. When
both its direct descendants (zebus) and closest relatives (taurine cattle, the
other two aurochs subspecies, other Bos,
Bison or buffaloes) show a specific
trait, it is almost certain that namadicus
had it as well because it is the most parsimonious and therefore most likely
assumption. For example, almost all wild bovines show a more or less slanted
pelvis that we also find in zebus. So it is very likely that the Indian aurochs
also had a slanted pelvis creating a rounded rear (perhaps not that extreme as
in some zebus). A more horizontal pelvis seems to be an autapomorphy of the
taurine clade that might have originated in Bos
primigenius primigenius or the common ancestor ofafricanus
and primigenius already, and probably
was also transferred to the wisent by hybridization (the wisent seems to be a
hybrid species of Eurasian aurochs and Bison
priscus [4]).

Very likely
the Indian aurochs was a long-legged animal with a square-like build. It is a
common trait in wild bovines and zebus also often are comparably long-legged
(or actually short-trunked compared to derived taurine cattle). Most likely the
Indian aurochs also possessed the high processus spinosi in the shoulder region
for large muscles to attach – a universal, functional trait for wild bovines
and evident in each single skeleton of Eurasian aurochs. The size of this hump
(not to be confused with the zebuine hump, I’ll come back to that later) might
have been different in namadicus, it
might have been larger or smaller. One would have to look at the relative
length of those processes if some are preserved.

Zebuine
cattle have the same E+
allele that is also found in taurine cattle causing wildtype colour, so it very
likely was the base colour for the Indian aurochs as well: lightly coloured
muzzle ring and dorsal stripe, degree of Eumelanin dependent on testosterone
level. Probably the colour was very similar to the European aurochs, but not
totally. The allele(?s) that regulate the distribution of the pigment in the
coat seem to have diverged a bit in zebus. For example, in taurine cattle the
snout is strongly melanised all the way down to the muzzle ring, creating a
sharp edge for the muzzle ring. In zebus there is more like a smoothtransition. In the less eumelanised individuals you do not see a saddle like in
taurine cattle, but a light area on the lateral side of the trunk that looks
similar to the saddle though. I call it the lateral zebu saddle. So there are
subtle differences that might have been inherited from namadicus as a result of the long time of divergence. Furthermore,
there are some zebuine colour modifiers as well, but we are going to look at
these in the next section.

Very likely
the Indian aurochs also showed a strongly marked sexual dimorphism. Sexual
dimorphism is universal to all other members of Bos (at least in the species whose life appearance is known),
although the dichromatism is quite reduced in most gaur populations. It is the
result of the social and mating system of large bovines (harem system), and I
have not heard of any differences in zebus on this aspect. So it is very likely
that namadicus also had a strongly
marked sexual dimorphism.

- Zebuine
traits that might be wildtype traits of namadicus

Zebuine
cattle have a lot of quite characteristic traits, and it is possible that some
of them might be in fact inherited from their wild ancestors. This suspicion is
especially strong if these traits are universal among zebus or at least very
common. These traits include:

- the
fleshy zebuine hump

- hanging
ears

- zebuine
colour modifiers

- the large
dewlap

However,
prevalence in the domestic population of the modern zebu alone is not an
argument for its presence in the Indian aurochs. The abundance of these traits
can also be explained if it appeared directly after domestication, was
preferred by artificial selection or became fixated by genetic drift. But if
those traits apparently serve a functional purpose, especially if this purpose
would have been advantageous for the Indian aurochs, we can speculate that they
are in fact wildtype traits.

The fleshy
zebuine hump, however, seems to serve no purpose for the animals. It is formed
by a hypertrophied Musculus rhomboideous and does not influence food storage or
thermoregulation [5]. It might actually be of disadvantage for the
animals because male zebus lack the big muscular neck bulge that is typical of
taurine bulls and many other large bovines as a consequence of the altered neck
musculature. Farmers use the hump of zebus to attach the plough on their
shoulders, so the zebuine hump might have been a mutation that was preferred by
farmers and is thus prevalent in zebuine cattle now.

Many zebus
have large, hanging ears. Hanging ears are, in various shapes, a typical trait
of domestic mammals of any species, so it was probably not a feature of the
Indian aurochs. We cannot rule out that its ears were a little bit lowered
compared to other bovines, but if so probably only to a shallow extent like in
this individual but not huge hanging ears like this cow has.

As for the
zebuine colour modifiers, it becomes a little bit more complicated. The Agouti allele that causes red
pigmentation to disappear and creates a grey colour is very widespread among
zebuine cattle, and I think it originated in the zebuine clade. Zebuine cattle
introgressed a lot into Steppe cattle which originated in the west of the
Eurasian steppe6, and the vestiges of zebuine introgression are very
apparent in their looks (upright horns, large dewlap). Probably the Agouti mutation found its way into
Steppe cattle by introgression from zebus. Steppe cattle further influenced
many other cattle such as those on the Balkans, Italy and the Alps. The Central
European breed Grauvieh shows the same Agouti
mutation, and it even found its way until the primitive Iberian breed Tudanca. The
Agouti mutation is likely a zebuine
allele, but is it a wildtype legacy of Bos
primigenius namadicus?

It is not
entirely impossible. Colour does not have such a great impact on evolutionary
fitness in large animals as in smaller animals, and genetic drift often play a
role as well, so it could well be plausible that the greyish colour of zebus
(i.e. the lack of red pigment caused by the respective Agouti allele) originated in namadicus.
But considering that it was a tropical bovine, I think it is less likely;
tropical animals often tend to be more melanised than those of temperate
regions (Gloger’s rule; however, one has to be careful with the so-called
ecogeographical rules; I am planning to do a post on that as well), and other
tropical bovines and bovids show very vivid colours as well. So I tend to think
the Agouti dilution allele is a
mutation that occurred after domestication. One would have to test this locus
on aDNA of B. p. namadicus (which
would be very difficult to acquire because of the preservation circumstances in
India).

Authors
also describe the so-called “zebu tipping gene” that causes a light colour on
the ventral side of the body (van Vuure, 2005). But I wonder if this is truly
confirmed to be an additional locus in zebuine cattle (and since Bantengs also
show very light areas between the legs, it could also be a basal gene that was
lost again in the taurine branch), or if the light ventral hairs we see in
zebuine cattle are just caused by an allele on a locus that is shared with
taurine cattle, since wildtype coloured taurine cattle also often have light
areas between the legs. It is actually part of this colour scheme, but to a
varying extent. In this case, we can only guess whether it was present in namadicus or not. The same goes for the
lateral zebu saddle for bulls.

Another
trait that is often displayed by zebus are white ocular rings. Ocular rings in
the adult stage are widespread among bovids, and in taurine cattle it is found
in many calves but often lost in adulthood. It is very common in wildtype
coloured zebu cows (also in taurine cows having the Agouti dilution; it is a stable trait in Tudanca cows), but rarely
also found in bulls, such as in this miniature zebu bull from Germany (photo by
Markus Bühler):

The bull at the right has a plausible colour scheme for Indian aurochs
(photo: Markus Bühler)

However,
miniature zebus might be prone to display juvenile traits, what might be the
reason for this bull having ocular rings. Here once again we can only speculate
if adult Indian aurochs had ocular rings, and if only the cows had them or even
the bulls as well. A colour scheme like that one shown by the bull encountered
by Markus Bühler looks really aesthetic to me, it also has the lateral saddle
and the lightly coloured ventral side, and also looks very credible for a
tropical bovid. But we cannot know.

The large
dewlap is another typical, universal zebuine trait. Eurasian aurochs evidently
had a short dewlap, and according to stone engravings that of African aurochs
was short as well. Nevertheless, I do not rule out that the Indian aurochs was
the subspecies with the largest dewlap, at least for bulls. It is a general
rule that bovids/bovines in tropical climates tend to have large dewlaps for
display and perhaps also thermoregulation, while it is counteracting in
temperate climates (heat loss), which is why bovids/bovines in temperate
climates tend to have furry ornaments like beards or manes. So the dewlap of
the Indian aurochs might have been actually a little longer, perhaps comparable
to that of gaurs, bantengs and koupreys and was later exaggerated in zebus. It
could have also been as long as in zebus. We cannot know because do not have
unambiguous art that could give us a clue. I like to restore B. p. namadicus with a dewlap that is
comparable to the related bovines I just named.

Interestingly,
while the European aurochs reportedly had frizzy forelocks which are found in
many taurine breeds, no zebu has this trait. This matches with the assumption that
furry ornaments are a characteristic of bovids in temperate climates
(additionally to that, I have the little suspicion that the curly forelocks
might be a consequence of bison introgression into European/Eurasian aurochs;
we know that aurochs and bison hybridized, it must not have happened
exclusively in one way).

All in all,
the picture we have of the Indian aurochs is not that frustratingly incomplete
as the bone material we have because we can infer some things; we know that it
was smaller in overall size but had large and wide-ranging horns that were a
bit more upright, it probably had a typical morphology of a wild bovine and
thus was comparable to the other two aurochs subspecies, it probably had a
similar base colour and sexual dimorphism but we have to be unsure about some
details of its colour or the length of the dewlap.

Taking all
that into account, I created this new reconstruction of a bull and a cow (I
was, surprisingly, inspired by this photo of two English longhorns for
perspective and stance). I decided to do two versions: one showing a bull with
the zebuine lateral saddle and one without.

Using zebuine cattle in breeding-back

In the
previous posts on the Indian aurochs, I suggested doing a “breeding-back”
project with zebuine cattle. Looking at modern zebus, it is apparent that there
are seemingly no truly primitive zebus left that resemble their ancestor to a
large degree. This could be the result of genetic bottlenecks or very strong
artificial selection. But it should be possible to select on traits that we
know or can infer with a high degree of certainty. I suggest a mix of Watussi
(for the horns), miniature zebus with taurine influence as few as possible (for
the colour) and autochthonous Indian zebus like Guzerat/Krankeji, Kenkatha and
Javari. It should be possible to fully reconstruct the horns of namadicus especially with the aid of
Watussi, to get the right colour scheme also with some degree of sexual
dichromatism, and a square-shaped build. Obvious domestic traits like overly hanging
ears or a hanging spine should be avoided.

I did a
photo manipulation by painting suitable Watussi horns on a photo manipulation by
Jochen Ackermann on Wikimedia commons he did using a Taurus bull and a zebu:

That is
what I envision such a “breeding-back zebu” to look like. For some aspects,
such as the presence of the lateral saddle, no strict standards should be set,
because we do not know about their presence in the wildtype. The funny thing
is, I came up with the idea of a zebu “breeding-back” project in a dream were I
saw zebus that looked exactly like the photo manipulation above back in 2011.
Such a project should best be carried out in India so that the animals are
automatically suited ecologically. Releasing them on a sufficiently large area
size and leaving them exposed to natural selection will certainly alter their
morphology in a way that could provide us some clues on the wildtype. Their
morphology would become more like those of wild bovines, their horn shape might
become refined, and perhaps even the zebuine hump might disappear after some
generations if it really serves no purpose to the animals. It would be very
interesting to watch that.

But this
section is also about using cattle with zebuine influence in existing “breeding-back”
projects focusing on European aurochs. It is controversial and especially focusing
on the use of Watussi. I see that in my comment sections and also forum
discussions. People often have objections against cattle with zebuine influence
because the zebuine clade diverged a very long time ago, zebus have a pretty
divergent morphology, and are adapted to arid and hot climate – not what is
needed in Central or Northern Europe. Those are good reasons to be averse to
cattle with zebuine influence in “breeding-back” projects for the European
aurochs, but now I am going to explain my point of view to this subject very
clearly.

First of
all, and most important to note, the fact that they belong to a clade that
diverged long time ago per se does not imply cattle from this lineage have to
be destructive. Actually, if the Indian aurochs was still extant but the
European one extinct, I would use it in “breeding-back” projects at any time in
order to get beneficial wildtype traits.

Zebuine
cattle have a very derived morphology, that is true. But for “breeding-back”
projects, I do not care if an undesired allele is of zebuine or taurine
domestic origin, because it is undesired in any case. The recessive Agouti allele, that is widespread in any
“breeding-back” project/breed, is not desired for the European aurochs, no
matter if it originated in taurine cattle, zebuine cattle, or even the Indian
aurochs – so it makes no difference. The zebuine hump is not desired for the
European aurochs, in the same way the overly long hair of Highland cattle or
the virtual lack of sexual dichromatism in Sayaguesa is not desired for the
European aurochs – again, it makes no difference on which clade this mutation
originated because it is not desired in the population anyway.

The next
and very important point is that whatever undesired trait you introduce to the
population, you can breed it out again. The fact that zebuine cattle are
adapted to hot and arid climate, and therefore have a short and less dense coat
and less subcutaneous fat does not mean that using zebuine cattle will result
in all crossed cattle being less well adapted to cold and wet environments but
the traits are going to split up in the second cross generation and you have to
pick the right individuals – just as with any undesired and desired traits.
Steppe cattle, for example, are heavily influenced by zebuine cattle yet they
are among the cattle that are best-suited to cold habitats and have a supreme
winter coat, which is why they are used in all “breeding-back” projects.
It not only depends on what you crossbreed, but also on what you select for.

The amount
of desired vs. undesired traits of course implicates how to use a breed. To
give an example, I take the Watussi crossbreeds in the National Park Hortobagy.
I was told that second-generation crosses with Watussi influence often turn out
unsatisfying. This is not surprising: Watussi have a number of undesired traits
(zebuine hump, zebuine body, large dewlap) versus one desirable trait (horn
size). So the likelihood for a second-generation cross to end up disappointing
is larger than for it ending up pleasant. But that does not mean that Watussi
is not a good choice for breeding, not at all. It means that the breed has to
be used a bit more cautiously than breeds with a lot of desired traits and that
one has to be a bit more patient and lucky to get really good second-generation
crosses.

It is rare
that Heck cattle can serve as an example for efficient selection, but the
Wildgehege Neandertal, a German zoo, did a very good job in creating and
spreading very large-horned Heck cattle without maintaining any of the
undesired Watussi traits. They did this by using one Heck x Watussi cow in the
1950s, and using her quarter Watussi son as a breeding bull. While the other
Watussi traits got reduced to almost nil after decades, they always kept those individuals
with large horns. Nowadays there are a lot of Heck cattle that look totally
taurine but have impressively large horns like aurochs. Only in a few you can
see the Watussi descent (like this Bavarian Heck bull), but as I said, I regard
an undesired domestic zebuine trait not anymore worse than undesired domestic
taurine traits. The Neandertal lineage left a big mark on the German Heck
cattle population and it did not have any negative effects on the cold
tolerance of the cattle at all.

So I see no
problem with using a breed that is either zebuine or zebuine influenced if it
contributes precious traits. One just has to know how to use it wisely and
breed out the negative traits, just with any other breed.

About this blog

This blog is on everything related to the so-called “breeding-back” of extinct animals: From the extinct animals themselves, over their often domestic descendants and dedomestication to news and facts about various breeding-back projects, reports and photos from my own breeding-back related trips. I try to have a balanced and fact-based approach to this subject and to dismantle many of the popular myths. Enjoy!

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About me

My major interest always have been extinct animals, from dinosaurs to Pleistocene megafauna and more recent extinctions. Besides that I am interested in evolution, genetics and ecology.
I am also an amateur animal artist, making drawings and models mostly of extinct animals.